1. Field of the Invention
The present invention relates to a structure of connecting a flash memory card specification unit with a USB unit in a flash memory card by a rigid flexible board, and more particularly to a flash memory card having a communication interface in compliance with the specification of the flash memory card disposed at one end and a communication interface in compliance with the specification of a universal serial bus (USB) on the other end, and electric signals between the two communication interfaces are connected by a rigid flexible board (RFB), and a specific height difference is maintained between the planes of the two communication interfaces.
2. Description of the Related Art
Flash memory is a non-volatile memory having the advantage of retaining data after the power is turned off, and also possessing the advantages of a volatile memory that can be read and written repeatedly, and comes with a high capacity (quantity data stored in unit volume). The flash memory can be built in an electronic device, or expanded for larger memory size, and thus the flash memories are packaged according to different specifications. In other words, the flash memory cards include Compact Flash (CF) card, Smart Media (SM) card, Multi Media Card (MMC), Memory Stick (MS), and Secure Digital (SD) card, etc.
In the meantime, the practical applications of the flash memory card covers the areas of mobile phones, flash memory sticks, MP3 players, and digital personal assistants (PDA), etc. Since there are various different specifications, the flash memory cards come with different lengths, widths, and communication interfaces (pins); for example, the Compact Flash (CF) card has 50 pins for its communication interface, the Smart Media (SM) card has 22 pins for its communication interface, the Memory Stick (MS) card has 10 pins for its communication interface, and the Secure Digital (SD) card has 9 pins for its communication interface. Although there are 6-in-1 and all-in-one card readers in the market, the design of these card readers must have several card slots and interface contact points according to various different formats of the flash memory cards. The more the specifications of the memory cards, the more complicated are the designs, and thus the higher is the cost of the card readers.
Refer to FIGS. 6 and 6a for the improvements of the foregoing shortcomings and the integration of a popular memory card such as a Secure Digital (SD) card having a higher capacity and a smaller volume with a popular common Universal Serial Bus (USB) communication interface, in hopes of allowing the Secure Digital (SD) card to concurrently have two kinds of communication interfaces. Since the heights of the SD communication interface of the SD card and the USB communication interface are different, the USB communication interface is bent upward to overcome the height difference between these two communication interfaces to match with the USB connector. On a rigid printed circuit board 70, the SD communication interface 80 and USB communication interface 60 are soldered, and a 90-degree continuous bending is formed at the USB communication interface 60 and extended outward (as shown in FIG. 6a) to solve the problem of having a height difference between the SD communication interface 80 and the USB communication interface 60. However, the external plugging and unplugging forces are exerted directly onto these communication interfaces, the communication interfaces will be cracked or broken at the bent position very easily after the communication interfaces have been used for a while, so that the USB communication interface 60 will be short-circuit and unable to transmit information.